This invention relates to a method for repelling animals or birds from large areas of land or wooded areas and to a composition for this purpose.
Among the natural hazards to aviation are deer and birds. Birds are particularly hazardous when an airport is located close to a garbage dump. Several airplane crashes have been attributed to flocks of birds, which circle in the landing pattern or near the ends of the airport runway. Other airports are located in wooded areas and have large grassy areas adjacent to the runways, which areas are extremely attractive to deer and other ruminating animals which graze in open or wooded areas.
Birdstrike and deerstrike can cause considerable economic damage as, for example, damages amounting to $250,000 to a Beech 99 mail plane which struck a deer on its landing rollout at a Pennsylvania airfield. In the winter season of 1976-1977, one of five deerstrike accidents at Dulles International Airport included an encounter with a B-707 during the takeoff run. It will be appreciated that for every case in which physical contact and property damage by deerstrike or birdstrike occurred, there are several "near misses", which are necessarily harrowing occurrences to the pilots of the aircraft involved and to the operators of the airport facilities. See, E. A. Jerome, "The Deerstrike Hazard," Airport Safety Bulletin, March, April, 1977, Flight Safety Foundation, Inc., Arlington, Va., 22209, for a description of unsuccessful procedures for preventing deerstrike.
Zinc dimethyldithiocarbamate, tetramethylthiuram disulfide (Littler, U.S. Pat. No. 3,060,084) and dithiocarbonic acid O-ethyl-S-[2-(p-chlorophenylmercapto)chloropropyl ester] (Schrader et al., U.S. Pat. No. 3,686,257), the disclosures of which are herein incorporated by reference, are among known animal or bird repellant material. The Littler patent indicates that polycarboxylated hydrocarbon polymeric suspending agents are used in combination with a dispersing agent.
Stone (U.S. Pat. No. 3,663,253) employs aluminum salts in animal deterrent composition. Kenaga (U.S. Pat. No. 3,389,048) teaches the use of tricyclohexyltin compounds as a repellant for feeding mammals. Hawthorne et al., (U.S. Pat. No. 2,971,962) indicated that 2-hydroxybiphenyl-2'-carboxylic acid lactone is useful as a rodent repellent. Wicker, Jr. et al. (U.S. Pat. No. 2,933,429) employs ethylene dinitriles and esters of ethylene dicarboxylic acid esters for the same purpose.
Needham et al. (U.S. Pat. No. 3,694,543) and Woodruff (U.S. Pat. No. 3,740,201) disclose the formulation of various animal repellant compounds with olefin polymers and copolymers.
It will be appreciated that materials applied to grazing areas or wooded areas from which it is intended to repel birds, deer or other objectionable animals must not interfere with the life processes of the grassy areas, i.e., the material must permit transpiration and photosynthesis. It is also apparent that any material applied to grassy areas, or to the runways of an airport or to any other locus being protected should be stable and adhere relatively persistently to the area being protected, so that frequent applications of the repellant material are not required.
Materials which have been applied to plants or grass, for various reasons, including prevention of loss of water by transpiration, include wax emulsions, as practiced by Cushman (U.S. Pat. No. 3,847,641), liquid polyterpenes, Clark et al (U.S. Pat. No. 3,676,102), polymers made from isocyanates as taught by Cooke (U.S. Pat. No. 3,539,373), long chain esters of lower organic acids as suggested by Gabor (U.S. Pat. No. 3,199,944) and soluble carboxylated polymers, for example, derived from Cellosolve.RTM. acrylate and methacrylic acid as taught by Ferguson (U.S. Pat. No. 3,157,964). Klaas (U.S. Pat. No. 3,089,280) discloses the treatment of plants with an acrylic-based light-affecting composition containing optical brighteners. However, each of these compositions has one or more deficiencies. For example, the polymers used by Gabor are highly soluble, so that frequent applications are required to maintain effective protection against excessive transpiration. Although the main purpose of the Klaas coating is to produce a hard and brilliant finish on plants, the desired effect is achieved only by at least two coatings applied at intervals of about two to four weeks.
Polymer coatings have been applied to plants for other purposes, such as the coloring of grass. However, according to the teachings of Converse (U.S. Pat. No. 2,870,037) and Gardner (U.S. Pat. No. 2,786,821), the grasses so treated seem to have been protected from deterioration or crumbling through mechanical action of the polymer.
It is therefore apparent that although products are available which are essentially soluble and which are easily applied to grass or plants, such products are washed from the sprayed plants after an unpredictable time interval based primarily on the frequency of rainfall. Known compositions must therefore be reapplied frequently to maintain their efficacy. Furthermore, most of the known products have varying stability to ultraviolet radiation in sunlight, so that the products deteriorate and then wash away. There is at present no product applied to the leaves and stems of plants which has an active applied life exceeding much more than about three weeks.
Therefore, there is a continuing need for animal and bird repellant compositions which are easily applied to grassy areas, wooded areas or runways of airports, to dumps adjacent to airports or to grassy and wooded areas adjacent to highways, which are relatively persistent once applied and which have no deleterious effects on the surfaces to which they are applied.